The Geritol Solution
Part I

By Debra Allen PhD., University of Delaware, Problem-based Learning Clearinghouse
Modifications by John S. Peters, College of Charleston

    John H. Martin, then director of the Moss Landing Marine Laboratories in California, suggested that we could lessen the threat of global warming by dumping iron into the waters off Antarctica. "Give me half a tanker of iron and I'll give you an Ice Age," he (only half-jokingly) remarked during a lecture before an audience of scientists at the Woods Hole Oceanographic Institute in 1988. Martin proposed that by spiking the Southern Ocean with 300,000 tons of iron, we could remove about two billion tons of carbon dioxide from the atmosphere. 

    Why iron? The origin of the "Geritol solution," as Martin's scheme later came to be known, is rooted in a longstanding speculation among biogeochemists. They wondered why the so-called HNLC (high-nutrient, low chlorophyll) waters or "desolate zones" of the Southern ocean around Antarctica and of the equatorial and subarctic Pacific are so barren (low in biological productivity), despite their seeming abundance of nutrients.  Martin pieced together information about the sources and distribution of iron in open ocean waters and iron's solubility in water, and proposed that a low iron concentration limits productivity in these otherwise fertile areas. 

    Development of a way to measure the minuscule amounts of iron present in seawater led to a series of "iron in a bottle" experiments designed to test the basic premise of this iron availability hypothesis. The results of the first of these experiments showed that the amount of chlorophyll found in ocean water samples collected from the Gulf of Alaska could be increased up to nine-fold by the addition of iron. A repeat of this iron seeding experiment with water samples collected from a few hundred miles off the Antarctic coast showed that for every unit of iron added to the seawater, the organic carbon content of the water increased by a factor of 10,000.

    When prominent skeptics were reluctant to accept these experiments, Martin (now referred to by some as "Johnny Ironseed" or the "Iron Man"), proposed to fertilize a test plot of the open ocean with iron. What would happen?

Questions to Consider:

  1. How urgent is the problem of global climate change?
  2. How would the effectiveness of the Geritol solution compare to other “solutions” to the global warming problem?  
  3. On what scale should we implement OIF and why?
  4. Can small scale (short term, small area) experiments reveal the potential large scale benefits or risks of OIF?
Identifying Learning Issues:

Learning issues are information/facts/concepts/assumptions/evidence that we will need to identify and examine further to better understand the problem. 
Good learning issues:

As you develop learning issues, ask yourself why you think this knowledge might be critical for resolving this problem, and be prepared to defend this to the rest of the class. 

  Comments, suggestions, or requests to Last updated 12 May 2010.  College of Charleston.